Multiple sheet detector mechanism for use with sheet-feeding apparatus



Aug. 1, 1950 H. T. BACKHOUSE 2,517,379

MULTIPLE SHEET DETECTOR MECHANISM FOR usE wrm SHEET-FEEDING APPARATUS Filed July 29, 1947 Patented Aug. 1, 1950 UNITED STATE MULTIPLE SHEET DETECTOR MECHANISM FOR USE WITH PARATUS SHEET FEEDIN G AP- Headley Townsend Backhous e,

Wentworth, England Section 1, Public Law Mama 8, 1946 Patent expires April 20, 1965 1 Claim.

This invention relates to sheet-feeding apparatus of the kind in which sheets of paper, card or the like are fed along a layboard or equivalent support up to a position at which registration of each sheet may be effected, for example by the usual front and side lays, after which each sheet is taken, usually by some form of gripper mechanism, to a printing press or other machine.

The present invention is concerned with the provisionfor use with sheet-feeding apparatus of the above kind-of an improved form of detector mechanism of the type comprising a socalled two sheet caliper arranged in such manner that if by accident two sheets or more adhere or for any other reason are fed together superimposed to or towards the front lays, the extra thickness will be detected and the feeding apparatus stopped.

The invention provides, in or for sheet-feeding apparatus of the above kind, a two-sheet caliper comprising a pivotally mounted lever extending, or arranged to extend, in the lengthwise direction of the layboard towards the front lays, and a gauge-piece (preferably in the form of a blade) carried by the lever and adapted to co-operate with the layboard, or a stationary part associated therewith, to form a gauge to pass a single sheet, but movable relatively to the lever on engagement by an extra superimposed sheet or sheets, and arranged on such relative movement to cause the operation of trip mechanism to stop feeding of the sheets. The lever may be arranged to be engaged by a cam movable in timed sequence with the main operations of the machine, to engage the lever each time a single sheet is received within the pass of the gauge and to lift the lever and with it the gauge-piece into a position to leave the sheet clear to be taken by the grippers of the printing or other machine. The lever may also carry a trip arm, constituting part of the trip mechanism aforesaid and arranged for co-operation with the movable gauge-piece in such manner that when the gauge-piece has been moved relative to the lever in consequence of a multiple sheet thickness entering the pass of the gauge, the trip arm will be moved into a position in which it acts as an abutment to intercept forward movement of the rocking cam and in consequence will stop the feeding apparatus.

An example embodying the invention and a modified form of this example will now be described with reference to the accompanying drawings in which Figure 1 is a side view of the detector mechanism;

.2 I ure 2 is a plan of the detector lever and associated parts,

Figure 3 is an end view of the bracket carrying the detector mechanism; and

Figure 4 is a view corresponding to Figure 1 of a modified form of the mechanism.

Like reference numerals indicate like parts in the several figures.

The mechanism shown in Figures 1-3 comprises a bracket slidably mounted on a stationary cross-shaft is located over the forward end of the layboard. A rearward extension of the bracket I embraces a second cross-shaft 3 to which a motion of partial rotation in a forward and backward direction is imparted in timed sequence with the main operations of the feeding apparatus. A downward extension of the bracket I carries a pivot pin Ill on which the detector lever 6 is mounted. The lever ii is capable of being adjusted towards or away from the layboard by means of an adjusting screw 4 operating against the pressure of a spring 5. The lever B carries a pivot pin 1 to which is hingedly attached, by means of a lug 8, the forward end of a steel blade 9.

The forward end of the blade 9 is downwardly constrained by means of a spring 18 located in a housing in the lever B, and the rear end of the blade carries a pin II which bears against one end of a trip arm it which is pivotally mounted at it on the lever B. The opposite end of the trip arm 12 bears on an abutment I4 forming part of the lever B and housed in the abutment is a light spring 20 which is just sufficiently strong to raise the trip arm in the event of the pin ll being lowered. A cam 2 is keyed at l! to the rock shaft 3, the forward profile 2] of the cam being shaped to engage with a roller [6 carried on a pin l5 supported by the lever B.

The mechanism is operated in the following Way. By adjustment of the screw 4 the lever B is so positioned that the gap between the blade 9 and the layboard is just suflicient to pass one sheet or card on its journey towards the front lays and in the event of two or more sheets passing superimposed beneath the forward end of the blade 9, this blade will be lifted, against the pressure of the spring l8 and in consequence the pin H carried by the rear end of the blade will be lowered out of engagement with the trip arm 12. By the pressure of the spring 2!! the trip arm will be lifted into a position in which it forms an abutment to engage and arrest the cam 2 on its forward motion. The arrest of the cam 2 is utilised, through appropriate clutch mechanism, to stop TENT OFFICE the feeding apparatus. Where only one sheet passes under the forward end of the blade 9, no movement of the blade relatively to the lever 6 will take place and the cam 2 will be free to continue its forward movement, engaging the roller I6 and consequently depressing the rear end of the lever B and raising the forward end into a position entirely clear of the sheet, thereby allowing it to .be taken freely into the printing press.

In the modification shown in Figure 4 the feeler blade 9 is swept upwardly at its rear end as shown at 30- and engages over a stop 3| adjustable in a lever 32, the lever being pivoted at l3 on the lever 6. In this modification if the blade 9 is lifted by two or more sheets passing between it and the layboard 33 it will pivot about the point 10 and its rear end will be lowered causing the lever 32 to be rocked about its support and to be moved into the path of the earn 2 as in the previous construction.

I claim:

In sheet feeding apparatus of the kind referred to, a two-sheet caliper comprising a pivotally supported lever extending in the lengthwise direction of the layboard towards the front lays, a blade pivotally supported on the lever intermediate in the length of the blade and arranged to form at one end of the blade a gauge-piece cooperating with the layboard to form a gauge to pass a single sheet but to be rotated about its pivot support on engagement by an extra superimposed sheet or sheets, a trip arm also pivotv ally supported on the lever and movable relative to the lever by the other end of the blade on rotation of the blade as aforesaid, a cam arranged to be continuously rocked in timed relation to the feeding of the sheets, the cam being arranged each time a single sheet has been fed and gauged to cooperate with a follower on the lever to rock the lever about its support to lift the blade clear of the sheet and if more than one sheet is fed and the trip arm moved as aforesaid to be intercepted by the arm and thereby to cause the feeding of further sheets to be stopped.

HEADLEY TOWNSEND BACKI-IOUSE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 765,414 Dexter July 19, 1904 2,298,368 Goebel et al Oct. 13, 194-2 

